This invention relates to aquatic articles that alternately ascend and descend and, more particularly, to an aquatic article for use in a water container, such as an aquarium.
It is known to use a gas to operate an alternately surfacing and submerging unrestrained aquatic toy or other article. See, for example, my U.S. Pat. No. 2,932,916 which issued Apr. 19, 1960. In one embodiment, such an article comprises a figure having a buoyancy chamber containing a gas-generating material, one or more downwardly directed water ports leading to the buoyancy chamber, and one or more upwardly directed gas vent openings leading from the buoyancy chamber. When the figure is completely submerged, a water-gas seal is formed across the vent openings by surface tension. As a result, the gas pressure in the chamber rises, water is expelled from the chamber, the specific gravity of the figure becomes less than one, and the figure ascends to the water surface. When the vent openings are exposed to the atmosphere at the water surface, the water-gas seal breaks. As a result, the gas pressure in the chamber drops, water enters the ports, the specific gravity of the figure becomes greater than one, and the figure descends until the specific gravity of the figure again becomes less than one. Then, the cycle repeats.
It is also known to use air supplied by the aeration pump of an aquarium to operate an article remaining at the bottom of the aquarium, such as, for example, a clam shell that is repeatedly opened and closed.